1. Technical Field
This invention generally relates to computer systems, and more specifically relates to apparatus and methods for accessing data in a computer database.
2. Background Art
Since the dawn of the computer age, computers have evolved and become more and more powerful. In our present day, computers have become indispensable in many fields of human endeavor including engineering design, machine and process control, information storage and retrieval, and office computing. One of the primary uses of computers is for information storage and retrieval.
Database systems have been developed that allow a computer to store a large amount of information in a way that allows a user to search for and retrieve specific information in the database. For example, an insurance company may have a database that includes all of its policy holders and their current account information, including payment history, premium amount, policy number, policy type, exclusions to coverage, etc. A database system allows the insurance company to retrieve the account information for a single policy holder among the thousands and perhaps millions of policy holders in its database.
Data is often accessed in a database using queries. A query is a statement in a particular syntax that specifies what data in the database to retrieve. A query processor typically processes a query and retrieves data from the database that matches parameters specified in the query. One particular type of query is known as a prepared statement, which is a query statement that contains variables. The prepared statement is used by specifying values for the variables, then executing the statement. Prepared statements enhance the efficiency of a query processor because once the prepared statement has been evaluated, it can be executed by the query processor using new values for the variables without having to perform all of the work to process the statement anew.
Some prepared statements are executed numerous times on data that does not often change. The use of the prepared statements reduces the work that must be performed by the query processor, but the data must still be retrieved from the database each time the prepared statement is executed. Without an apparatus and method that reduces the time to access data that seldom changes in a database, the computer industry will continue to suffer from excessive overhead in accessing database data.